Blood is a living tissue; transfusion of it or of its cellular components from a donor to a recipient is a form of transplantation. About 11 to 12 million transfusions are given yearly in the United States, and the number is steadily increasing. The decision to transfuse is a clinical judgment that requires weighing the possible benefits and known hazards with alternative treatments. A transfusion not specifically indicated is contraindicated.
In the United States, regulations for collecting storing, and transporting blood and its components are established by the Federal Drug Agency (FDA), and sometimes also by state or local health authorities. The American National Red Cross and American Association of Blood Banks also have standards affecting their respective systems. Screening a donor includes a health interview, testing for Hemoglobin (Hb), and taking the temperature, pulse rate, and blood pressure (BP).
Before use, blood must be classified for suitability. This includes ABO and Rh typing, antibody screening, STS, a test for hepatitis B surface antigen (HBsAg), and tests to detect antibodies to the virus that causes acquired immunodeficiency syndrome (AIDS). The container label and the federally required Circular of Information give the results of these tests and important information and cautions and should be consulted by physicians using blood transfusions.
The various components of blood can be separated, concentrated, and stored individually for precise replacement of patient needs.
Red blood cells (RBCs) are transfused to replace Hb or O.sub.2 carrying capacity, including blood lost at surgery, and to prime extracorporeal circuits. When volume expansion is required, other fluids can be used concurrently or separately.
Frozen-thawed RBCs are costly and mainly used for patients who have multiple blood group antibodies or antibodies to high frequency antigens.
Wasted RBCs (by continuous-flow washing) are free of almost all traces of plasma and of most white blood cells (WBCs) and platelets. They are suitable for patients who have severe reactions to plasma (eg, severe allergies or IgA immunization), or for those who have leucocyte antibodies and repeated febrile transfusion reactions.
The four ABO blood types are determined by testing for the presence or absence of A and B antigens on the RBCs using Anti-A and Anti-B reagents (forward or cell typing), and by testing for Anti-A and Anti-B in the serum using A and B reagents RBCs (serum or reverse typing).
There are several reactions that accompany or follow intravenous administration of blood or blood components.